package com.ctrip.framework.foundation.internals.provider;

import com.ctrip.framework.apollo.core.utils.DeferredLoggerFactory;
import com.google.common.base.Strings;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Properties;

import com.ctrip.framework.foundation.internals.Utils;
import com.ctrip.framework.foundation.internals.io.BOMInputStream;
import com.ctrip.framework.foundation.spi.provider.Provider;
import com.ctrip.framework.foundation.spi.provider.ServerProvider;
import org.slf4j.Logger;

public class DefaultServerProvider implements ServerProvider {

    private static final Logger logger = DeferredLoggerFactory.getLogger(DefaultServerProvider.class);

    static final String DEFAULT_SERVER_PROPERTIES_PATH_ON_LINUX = "/opt/settings/server.properties";
    static final String DEFAULT_SERVER_PROPERTIES_PATH_ON_WINDOWS = "C:/opt/settings/server.properties";
    private String m_env;
    private String m_dc;

    private final Properties m_serverProperties = new Properties();

    String getServerPropertiesPath() {
        final String serverPropertiesPath = getCustomizedServerPropertiesPath();

        if (!Strings.isNullOrEmpty(serverPropertiesPath)) {
            return serverPropertiesPath;
        }

        return Utils.isOSWindows() ? DEFAULT_SERVER_PROPERTIES_PATH_ON_WINDOWS : DEFAULT_SERVER_PROPERTIES_PATH_ON_LINUX;
    }

    private String getCustomizedServerPropertiesPath() {
        // 1. Get from System Property
        final String serverPropertiesPathFromSystemProperty = System.getProperty("apollo.path.server.properties");
        if (!Strings.isNullOrEmpty(serverPropertiesPathFromSystemProperty)) {
            return serverPropertiesPathFromSystemProperty;
        }

        // 2. Get from OS environment variable
        final String serverPropertiesPathFromEnvironment = System.getenv("APOLLO_PATH_SERVER_PROPERTIES");
        if (!Strings.isNullOrEmpty(serverPropertiesPathFromEnvironment)) {
            return serverPropertiesPathFromEnvironment;
        }

        // last, return null if there is no custom value
        return null;
    }

    //可以看到主要就是从2个固定的目录去读一个特定的文件，如果读不到，后续就是从系统变量和jvm取了
    @Override
    public void initialize() {
        try {
            File file = new File(this.getServerPropertiesPath());
            if (file.exists() && file.canRead()) {
                logger.info("Loading {}", file.getAbsolutePath());
                FileInputStream fis = new FileInputStream(file);
                initialize(fis);
                return;
            }
            initialize(null);
        } catch (Throwable ex) {
            logger.error("Initialize DefaultServerProvider failed.", ex);
        }
    }

    @Override
    public void initialize(InputStream in) {
        try {
            if (in != null) {
                try {
                    m_serverProperties.load(new InputStreamReader(new BOMInputStream(in), StandardCharsets.UTF_8));
                } finally {
                    in.close();
                }
            }
            initEnvType();
            initDataCenter();
        } catch (Throwable ex) {
            logger.error("Initialize DefaultServerProvider failed.", ex);
        }
    }

    @Override
    public String getDataCenter() {
        return m_dc;
    }

    @Override
    public boolean isDataCenterSet() {
        return m_dc != null;
    }

    @Override
    public String getEnvType() {
        return m_env;
    }

    @Override
    public boolean isEnvTypeSet() {
        return m_env != null;
    }

    @Override
    public String getProperty(String name, String defaultValue) {
        if ("env".equalsIgnoreCase(name)) {
            String val = getEnvType();
            return val == null ? defaultValue : val;
        }
        if ("dc".equalsIgnoreCase(name)) {
            String val = getDataCenter();
            return val == null ? defaultValue : val;
        }
        String val = m_serverProperties.getProperty(name, defaultValue);
        return val == null ? defaultValue : val.trim();
    }

    @Override
    public Class<? extends Provider> getType() {
        return ServerProvider.class;
    }

    private void initEnvType() {
        // 1. Try to get environment from JVM system property
        m_env = System.getProperty("env");
        if (!Utils.isBlank(m_env)) {
            m_env = m_env.trim();
            logger.info("Environment is set to [{}] by JVM system property 'env'.", m_env);
            return;
        }

        // 2. Try to get environment from OS environment variable
        m_env = System.getenv("ENV");
        if (!Utils.isBlank(m_env)) {
            m_env = m_env.trim();
            logger.info("Environment is set to [{}] by OS env variable 'ENV'.", m_env);
            return;
        }

        // 3. Try to get environment from file "server.properties"
        m_env = m_serverProperties.getProperty("env");
        if (!Utils.isBlank(m_env)) {
            m_env = m_env.trim();
            logger.info("Environment is set to [{}] by property 'env' in server.properties.", m_env);
            return;
        }

        // 4. Set environment to null.
        m_env = null;
        logger.info("Environment is set to null. Because it is not available in either (1) JVM system property 'env', (2) OS env variable 'ENV' nor (3) property 'env' from the properties InputStream.");
    }

    private void initDataCenter() {
        // 1. Try to get environment from JVM system property
        m_dc = System.getProperty("idc");
        if (!Utils.isBlank(m_dc)) {
            m_dc = m_dc.trim();
            logger.info("Data Center is set to [{}] by JVM system property 'idc'.", m_dc);
            return;
        }

        // 2. Try to get idc from OS environment variable
        m_dc = System.getenv("IDC");
        if (!Utils.isBlank(m_dc)) {
            m_dc = m_dc.trim();
            logger.info("Data Center is set to [{}] by OS env variable 'IDC'.", m_dc);
            return;
        }

        // 3. Try to get idc from from file "server.properties"
        m_dc = m_serverProperties.getProperty("idc");
        if (!Utils.isBlank(m_dc)) {
            m_dc = m_dc.trim();
            logger.info("Data Center is set to [{}] by property 'idc' in server.properties.", m_dc);
            return;
        }

        // 4. Set Data Center to null.
        m_dc = null;
        logger.debug("Data Center is set to null. Because it is not available in either (1) JVM system property 'idc', (2) OS env variable 'IDC' nor (3) property 'idc' from the properties InputStream.");
    }
}
